Intermittent web feed mechanism with trigger stop



Oct. 4, 1966 c. A. LEWIS, JR" ETAL 3,276,648

INTERMITTENT WEB FEED MECHANISM WITH TRIGGER STOP Filed May '7, 1964 3 Sheets-Sheet l FIGI FIGZ INVENTORS CLARENCE A. LEWIS JR BY JAMES E O'BRIEN ATTORNEYS Oct. 4, 1966 c. A. LEWIS, JR, ETAL 3,276,648

'INTERMITTENT WEB FEED MECHANISM WITH TRIGGER STOP Filed May '7, 1964 3 Sheets-Sheet 2 I M 8 sii fi' 3 w} HQ; 5 0

I A L l 4/I26 MA iii 1 l I J FIG? LIVE GATE 1 W INVENTORS CLARENCE A. LEWIS JR.

BY JAMES F. O'BRIEN ATTORNEYS Oct. 4, 1966 c. AQLEWIS, JR, ETAL 3, 76,6 8

INTERMITTENT WEB 'FEED MECHANISM WITH TRIGGER STOP Filed May 7, 1964 5 Sheets-Sheet 5 Q: l-[WU Wv-{i g *-'V\N+ i I i 5 E w E INVENTORS Q5 CLARENCE A.LEWIS JR 1L JAMESF. O'BRIEN LL ESEN 5v fig WMM ATTORNEYS United States Patent 3,276,648 INTERMITTENT WEB FEED MECHANISM WITH TRIGGER STOP Clarence A. Lewis, Jr., Kinnelon, and James F. OBrien,

Sussex, N.J., assignors to Champlain Company, Inc.,

Roseland, N.J., a corporation of New Jersey Filed May 7, 1964, Ser. No. 365,754 21 Claims. (Cl. 226-33) This invention relates to intermittent web feed systems, and more particularly to a photo-electrically timed web clamp arrangement to improve the accuracy of such systems.

There are machines which feed a Web continuously at one point, and intermittently at another. An example is the combination of a rotary printing press with a reciprocating press which scores, creases, punches or cuts a printed web. For brevity the term punch is here used for all such operations. The punch press works on an intermittently stationary web, but the web is moving at constant velocity in the printing press.

It has already been suggested in US. Patent 3,025,740, issued March 20, 1962, to change the variable speed cycle of the web to provide a brief interview of low uniform velocity just before the dwell period, and to combine that with a clamp or so called trigger stop which stops the web at the desired instant during the brief interval of low velocity movement. The variable speed drive may be mechanical, but the clamp is controlled by a photoelectric eye or scanner which responds to a target printed on the web, and does so at a point close to'the punch press, thereby insuring accuracy of cut-to-p-rint registry.

The general object of the present invention is to improve such a system, and more particularly the clamps and the electrical control circuitry for operating the clamps.

To accomplish the foregoing general object, and other more specific objects which will hereinafter appear, our invention resides in the intermittent web feed mechanism, and the elements thereof, and their relation one to another, asare hereinafter more particularly described in the following specification. The specification is accompanied by drawings in which:

FIG. 1 is a side elevation drawn to small scale showing apparatus utilizing the present invention;

FIG. 2 is a fragmentary section explanatory of one form of variable speed drive which may be used as a part of the present invention;

' FIG. 3 is a schematic view explanatory of the invention;

FIG. 4 is a graph showing the variable speed of the web;

FIG. 5 is a plan view of one of the clamps;

FIG. 6 is a vertical section through the clamp;

FIG. 7 is a block diagram for the system; and

FIG. 8 ,is an electrical diagram for the system.

Referring to the drawing, and more particularly to FIG. 1, the machinery may be driven by a main drive shaft 12, which extends lengthwise of the moving web 20. Shaft 12 is driven by a main driving motor 14 (FIG. 3), operating through belts, chains or gearing indicated at 16.

The web 20 isacted on by a series of color printing units, which may be of the gravure type. Two such units are here shown at 22 and 24 in FIG. 1. They may be conventional, and may include driers at 23 and 27. Each has a gravure cylinder '26 (FIG. 3) driven by main shaft 12 through gearing indicated at 28. Mechanism, including electric eye scanners 30 (FIG. 1), may be provided between successive printing units to maintain the different 3,276,648 Patented Oct. 4, 1966 "ice colors in registration, and for this purpose, the gearing symbolized at 28 (FIG. 3) may include an appropriate running register, preferably of the planetary or differential gear type, which permits the automatic feed of a slight positive or negative motion from correction motor 29 to maintain registration.

The printed web is fed to a punch press 32 by means of an intermittent feed roller 34, cooperating as usual with an idler 36. The press 32 is driven by the main shaft 12 through appropriate gearing at 38, and serving to reciprocate the punch, as by means of connecting rods (not shown) leading to eccentrics on the punch press shaft 42. The intermittent feed roller 34 is also driven from main shaft 12, as by means of gearing in box 44 and change gear box 45 and box 46, the latter including appropriate cam or like mechanism to convert the continuous rotation of shaft 12 to an intermittent rotation of roller 34. Feed roller 34 preferably has a small overfeed or slippage when the web is stopped.

The apparatus includes a web pull unit using a pull roller 48 which is driven from the main drive shaft 12 through gearing at 50, driving a change gear box 52, and differential gearing 54, to shaft 76. Pull roller 48 cooperates with an idler 56. A loop of Web is provided at 58 between the uniform velocity pull roller 48 and the intermittent feed roller 34. During each cycle this loop grows slack, say to the dotted line position 58', during dwell at intermittent roller 34, and then the loop is taken up and reduced to minimum dimension. If desired, this latter position of the loop may be determined by a fixed stop cylinder 60. In such case, tension builds up between the intermitten feed roller 34 and the pull roller 48, as deter-mined by the position of the stop cylinder 60, and the web then may slip slightly at the intermittent feed roller 34, which usually has a slight intentional overfeed.

To correct or maintain the overall or average register, a compensator roller may be interposed between the last printing unit and the pull roller 34. In this case the stop roller 60 is use-d also as a compensator roller, instead of being truly fixed. The vertical position of compensator roller '60 is controlled by a correction motor 62, driving vertical scews 64 which raise or lower the end bearings of the compensator roller 60. This could be under control of a separate web scanner, located bet-ween feed roller 48 and intermittent feed roller 34, and cooperating with a suitable phase detector mounted on or geared to the punch press shaft 42, for one-to-one rotation with that shaft. The phase micrometer is here indicated schematically at 66. In the present case, the web scanner is located at =68, and the scanner is used primarily for the clamp action. The circuitry for triggering the clamp is described later, but not the circuitry for controlling register motor 62, and the latter may be controlled by a separate scanner with conventional circuitry which requires no description.

The pull roller 48 usually is so selected (or so driven) that its peripheral speed very slightly exceeds that of the printing cylinder 26, and therefore the web is kept under tension therebetween. The change gear box 52 includes change gears to accommodate changes in the length of the sheet or print, so that it will not be necessary to change the diameter of the roller 48 for each different print length.

The change gear box 52 preferably is supplemented by a drive of the positive infinitely-variable type so that very fine adjustment of gear ratio may be obtained. In the present case, main shaft 12, through gearing 70, drives a positive infinitly-variable drive 72, in this case a Graham drive, which through shaft 74 feeds a small motion into the differential gearing at 54, thereby modify- =3 ing the speed of feed roll 48 in fine degree under control of a hand wheel 76.

A similar fine speed adjustment is not provided for change gear box 45 because the intermittent drive must remain locked in phase relation to the punch press 32, and therefore a geared drive is needed. The change gear box 45 is arranged for small changes, and any residual discrepancy is put into the overfeed and slippage at roller 34, as previously mentioned.

Referring to FIG. 2, the variable feed mechanism (represented by box 46 in FIG. 3) is of the type disclosed in McIlvain Patent 2,658,406 and it includes a cam 82. The shape of the cam in the region 84 produces a brief interval of uniform low velocity immediately preceding the dwell period.

This is illustrated by the graph shown in FIG. 4, which is characterized by acceleration 86 and uniform high velocity 88, followed by a deceleration 90, which is discontinued when a very low velocity is reached, and the low velocity is maintained for a brief interval, as is indicated at 92. Thereafter the web is again decelerated at 94 to bring it to Zero velocity shown at 56. The deceleration 94 may be called stoppage to distinguish it from the main deceleration 90. The average web speed is indicated at 52', this being the speed in the printing press. The interval 92 of uniform low velocity is suitably located to straddle the desired clamp instant. The web target comes under the scanner, and the clamp stops the web, during this low velocity movement. The clamp is released before renewed acceleration begins.

Reverting to FIG. 2, and considering the variable speed drive in greater detail, the power input is at pinion 96, meshing with a gear 98, which revolves the pivot 100 of a planet gear 102, meshing with a sun gear 104. Inasmuch as planet gear 102 turns only a fraction of a revolution on the said pivot 100, the planet may be mutilated, leaving only a sector of a gear, as shown. The sector 102 is aflixed to an arm 106 oscillatable about pivot 100. Arm 106 carries a cam follower roller 108 which is received in the cam groove 82 previously referred to. The cam and its groove are stationary.

The output is applied by sun gear 104 to a shaft 110 which leads to a bevel gear 112 meshing with a bevel pinion 114 which in turn drives a shaft 116 leading to bevel gear 118 meshing with bevel gear 120. The latter turns the feed roller 34 previously referred to.

Referring to FIG. 3, the scanner 68 is controlled by the previous operation on the web, in this case the printing on the web. There is circuitry indicated at 75 responsive to scanner 68 for precision web control by means of a pair of clamps 126 (one near each edge of the web) located near the punch press 32, and arranged to momentarily clamp and positively stop the web.

Referring to FIGS. and 6, the downwardly movable pad of the clamp 126 is indicated at 140, and is carried at the lower end of a vertically slidable rod 142 which is vertically slidable in bearings 144 and.146. The rod 142 carries a ferrous armature 148 which is shown in its raised position. This is pulled downward by a U-shaped magnet, the core of which comprises a yoke 150 with upright legs 152 around which coils 154 are placed. It will be understood that the armature 156 and the core 150, 152 are preferably built up of laminations in conventional fashion. The coils 154 may be rectangular, as indicated in FIG. 5.

The height and therefore the maximum travel of the armature 148 is adjustable by means of nuts 156, between which the armature is clamped. Rotation of the armature is prevented by means of a stationary guide 158 bearing against one end of the armature. The bearings and the guide are carried by a frame 160 secured to top plate 162, these parts preferably being non-ferrous. The top of the pad 140 may be fitted with a rubber O ring 164 acting as a bumper or stop. The pad and armature are normally raisedby means of a compression spring 166 disposed around the rod 142. They are pulled down when the magnet coils 154 are energized. The clamp is mounted so close to the web that the actual travel of the pad is reduced to a very slight amount, say 0.020 inch.

The phase micrometer 66 (FIG. 3) is a known device used in registration systems, it comprising an opaque disc or cup which rotates with the shaft, and which has a slot or window. A lamp is disposed on one side and a photodiode on the other side of the rotating element, so that an electrical pulse is delivered as the slot moves between the lamp and diode. The resulting live gate may be considerably wider than the narrow pulse obtained from the web scanner 68, but the latter must be coincident, and therefore the target on the web need not have a clear track, that is, other markings may appear on the web without affecting the scanner 68. In most cases, therefore, the selected target may be a part of the regular printed matter which is anyway being printed on the web.

In the present system, the live gate is given an additional function in that the trailing edge of the said gate is employed to terminate the energization of the clamp magnets in order to release the clamps.

Referring now to the block diagram is FIG. 7, the output of web scanner 68 is fed into a block 202 which provides for light increase or light decrease at the target on the web. The output of block 202 proceeds to an amplifier 204, at which the sensitivity of the amplifier can be selected. This pulse proceeds through a Schmidt trigger 206, the output of which is a pulse having constant amplitude and rise time. The Schmidt trigger pulse is combined at an inhibited AND gate 208. This gate is enabled by the live gate signal; that is, an output pulse will occur when the web pulse occurs, but only if the live gate pulse is present. (The term enable means that the gate is receptive to and permits an output; and the term inhibit means that it is not receptive or prevents an output.)

The leading edge of the live gate pulse sets flip-flop circuit 222, and through an inverter 220 (which produces an output which is the opposite Olf its input), appears at gate 208 as the enabling input. Thus a selected web pulse through gate 208 will actuate a one shot monostable multi-vibrator 210 to produce a pulse which is de-' layed in time. This delayed pulse proceeds to another one shot circuit 212, and actuates that circuit, and again a delayed pulse is produced. At this block 212 the first delayed pulse is utilized, and in turn appears at an AND gate 214. The otherinput to AND gate 214 is derived through a flip-flop circuit FF222 and an inverter 300, so that when both of the aforementioned pulses (meaning the first delayed pulse and the output of inverter 300) appear at gate 214, an output pulse is produced which is amplified through amplifier 216 and triggers a gate 218, which in urn actuates the four clamp coils for the two claimps 12 e For precision, the timing of the web clamp action must allow for delay in the magnet action. This delay is a constant, but the amount of Web travel will depend on the web speed. We therefore provide means to compensate automatically for changes in Web speed.

There is known circuitry to produce a delay, but not to produce an anticipatory lead time. Accordingly, an initial exaggerated anticipatory lead is mechanically provided, as by fixing the scanner location earlier along the web a distance corresponding to the maximum lead that may be needed (the lead needed for the highest web speed). Then by introducing a variable delay, the net effect is as thoughintroducing a variable lead time.

The one-shot mono-stable multi-vibrator '210' is the variable delay circuit. The magnitude. of. delay that is wanted is inversely proportional to the speed of the web. This is accomplished with the aid of a tachometer generator G driven in proportion to web speed, or in this case, by shaft 76 (FIG. 3) of feed roll 48. The output of generator G (FIG. 7) is supplied to the one shot circuit 210, preferably through a potentiometer R13, which may be located remotely, for final adjustment without moving the scanner, should such final adjustment be needed.

Referring now to FIG. 8, and specifically to the details of the circuitry, the block labeled 202 in FIG. 7 comprises in FIG. 8 the transistor Qland switch LI-LD (light increase-light decrease). vThe block labeled 204 in FIG. 7, comprises in FIG. 8 the transistors Q2, Q3, and switch S3. Transistors Q2 and Q3 provide amplification, and switch S3 selects the desired sensitivity, by connecting to either R11 or R12, which differ in value. The Schmidt trigger (206 in FIG. 7) in FIG. 8 centers around the transistors Q4, Q5, and Q6. The output of the Schmidt trigger proceeds to a one shot circuit (block 210 in FIG. 7) which in FIG. 8 centers around the transistors Q7 and Q8. The inhibited AND gate 208 in FIG. 7, in FIG. 8 centers around capacitor C1 and re sistor R1, the latter being connected by wires 230 and 232 to transistor Q9. If the collector voltage of transistor Q9 is close to ground, i.e., approximately zero, indicating that the live gate pulse is present, a pulse can combine from the output of the Schmidt trigger circuit centering about transistors Q4, Q5 and Q6 and through condenser Cl, and thereby actuate the one shot circuit centering on transistors Q7 and Q8. If, however, the collector voltage of transistor Q9 is high, approximately say 12 volts, indicating that the live gate pulse is not present, a pulse from the output of the Schmidt trigger will not fire the one shot circuit of transistors Q7 and Q8.

The DC. tachometer generator G provides an output voltage proportional to press speed. This voltage appears at diode D1, and through the RC combination of resistor R6 and capacitor C5, provides the proper time constant which in turn establishes the delay period of the one-shot circuit of transistors Q7, Q8. Thus, as the press increases in speed, a higher output voltage will appear at diode D1, which in turn produces a shorter delay period, as is desired.

The compensation produced by the multi-vibrator and generator combination is approximate, since neither is truly linear. However, the approximation is within the register accuracy required of the apparatus.

The delayed pulse appears through line 240 and actuates the other one-shot circuit based on transistors Q13 and Q14 (or block 212 in FIG. 7). However, this circuit is actuated in less than a microsecond, and therefore the output pulse on line 240 appears immediately at diode D3. (A (microsecond is negligible compared to the desired delay which is in milliseconds.)

When inputs at both diode D3 and diode, D4 are present, the trigger stops 126 are actuated through cascaded transistors Q15, Q16, Q17, Q18, and Q19. These five transistors have adequate current amplification to provide the several amperes required to energize the four magnet coils 126 of the clamps.

Thus, the clamp action is initiated in proper time relative to the target on the web to actually stop the web in registry with the die in the punch press. This variable lead time is made to occur during the low speed unilform velocity period 92 (FIG. 4) of the intermittent 'Web feed cycle. Without the uniform velocity interval, there would be no simple linear relation between time delay and web travel. This constitutes an additional advantage when using the special cycle shown in FIG. 4. t

However, a web clamp action could be used without clamp speed is one of the advantages of the present systern, although very high clamp speed is available from the present circuitry it wanted. A four-position switch S1 is provided for selection of clamp speed, so that the speed may be reduced in the event that marring of the web is noticed.

To release the magnets we employ the trailing edge of the live gate of the phase micrometer. The gate may be opened up or widened somewhat for this purpose.

The trailing edge of the live gate pulse from line 242 appears at transistor Q12, which is an inverter. The output of this inverter resets a flip-flop circuit which is in block 222 in FIG. 7, and which in FIG. 8 centers about transistors Q10, Q11. The inverter block 300 in FIG. 7, is Q20 in FIG. 8. There then is no further input to diode D4. This in turn de-activates the magnet coils 126 through the five amplifying transistors Q15 through Q19.

The clamp magnets have sufiicient holding power when energized at say six volts, but then would require too long to clamp the web. This clamp operating time is reduced by first hitting the magnets with a momentary high voltage, say seventy volts. The high voltage is obtained by discharge of a storage capacitor, and is so brief that it cannot harm the magnets.

Transformer T3 and the bridge circuit marked B2, in combination with capacitor C3, provides a 6 volt power source, which is utilized for the holding power required for the clamp coils. However, if this voltage were utilized in initiating the clamping cycle, the time constant of the coils would be approximately forty milliseconds. This would be excessive and objectionable inasmuch as accurate register would be difiicult to maintain. Therefore, a much higher voltage is made available through transformers T1 and T2, switch S1, rectifier B1, and the combination of resistor R2 and capacitor C2. This higher voltage is utilized only momentarily to initiate the clamping cycle in order to effectively reduce the delay time until the clamp comes in contact with the web. The resistor R2 has a high resistance (say fifty ohms) relative to the clamp coils (say one ohm) and therefore the higher voltage is applied only momentarily, and thereafter is lost across resistor R2.

The circuit functions as follows: The RC combination of R2 .and C2 establishes a time period at which the capacitor C2 will charge to 67% of the maximum voltage represented by the setting of switch S1. Thus, if the repeat rate of the press is, say three hundred strokes per minute, the time constant represented by circuit R2, C2 should be less than 0.2 second (the reciprocal of 300 divided by 60). The capacitor is charged to 67% of maximum voltage in each press cycle, this being a high voltage compared to the low holding voltage.

The initial voltage actually used may be varied by means of switch S1, here shown as having four positions or transformer taps. The high voltage with the switch S1 set in highest position 4 is approximately seventy volts in the present circuit. At the instant that the turn-on signal reaches transistor Q19, capacitor C2 is discharged through the clamp coils 126. Thus, a high energy pulse is avail: able to initiate the actuation cycle. If set at seventy volts, the effective time constant of the clamp circuit is reduced from, say, forty to less than four milliseconds. (This is computed by dividing the forty milliseconds by the voltage ratio of seventy to six, which comes out somewhat less than four milliseconds.)

When the capacitor voltage discharges to a value less than 6 volts, diode D6 becomes forward biased and conducts, and thereafter the power to hold the clamps is derived through transformer T3 and rectifier bridge B2, in combination with capacitor C3. Thus, rectifier or power diode D6 acts as an OR circuit to allow the higher of the two voltages (6 volts, or -70 volts from capacitor C2) to appear as a supply for the coils 126. Differently expressed, the diode D6 is polarized to isolate the two very different voltage supplies for the clamp cords.

It is also desirable to reduce the deactivation time constant (for fast magnet release) so that it is approximately equal to the actuation time consant, typically four milliseconds. This fast deactivation is accomplished as follows: When transistor Q19 is deenergized or turned off, the four magnet coils 126 act as .a current generator, and through the combination of diode D and resistor R3 provide a circuit such that a voltage is generated across resistor R3, the magnitude of this voltage being equal to the instantaneous coil current times the resistance value of R3. If this instantaneous coil-holding current were, for example, four amperes, and we made the value of R3 equal to 17.5 ohms, the voltage appearing across resistor R3 at the instant of deactivation would be equal to seventy volts. This would allow the coils to deenergize in the same time as is required to energize them. No attempt is made to release the magnets in less time, because of high voltage restriction as applied to transistor Q19.

If the press happens to be stopped with the clamps down, they would be overheated by continuous energization, for they are designed for brief intermittent energization or a low duty cycle. It could happen that the press stops at the live gate, in which case the coils might remain continuously energized. This would require that they be designed for 100% duty cycle, which would be a design disadvantage since the coils and their components would have to be unusually large. Here they may be small be cause they are energized only intermittently.

The purpose of the one shot circuit 212 in FIG. 7, which in FIG. 8 is represented by the transistors Q13, Q14, is to make sure that the magnet coils are never energized for a time greater than that represented by the time constant of the RC circuit F10, C10. This protects the coils against continuous energization. The requiremerit for the time constant represented by delay circuit R10, C10 is merely that the time be less than the highest repetitive rate ever required of the press, for example, three hundred strokes per minute or 0.2 second.

The transformer T4 and diodes D11 tnd D12 and filter capacitor C4 constitute a plus four volt power supply for reverse biasing all transistors in order to ensure that they will be non-conducting in the off condition. The ex tension of the 110 volt A.C. leads at the bottom of the diagram represents connections to additional power supply circuits like that just described, but which serve to supply the other voltages used in the circuit, namely, plus twelve volts, and minus twelve volts. These voltages are indicated at various points on the diagram and may be assumed connected to such additional power supplies.

It is believed that the construction and operation of our improved system, as well as the advantages thereof, will be apparent from the foregoing detailed description. The circuitry employs solid-state components and therefore is compact and trouble-free. The clamps are operated magnetically, thereby eliminating hydraulics and simplifying the mechanism required.

A time allowance is provided for delay in the action of the clamp magnets, and there is automatic compensation for a change in web speed in order to appropriately vary the said time allowance. The live gate, which is anyway employedfor the scanner, is additionally used to release the clamps. The magnets are small in dimension and relatively inexpensive, and yet exert adequate clamping force because they are designed for a low duty factor. Their action is greatly speeded by momentary application of an initial voltage very much higher than the clamp holding voltage, this initial voltage being obtained by discharge of a storage capacitor. Additional safety means cuts out even the much lower holding voltage after a time interval which exceeds the maximum time interval for normal release of the clamps by means of the live gate, on the rare chance of this happening, as by reason of the press stopping'at the live gate, or a possible circuit failure.

It will be apparent that while we have shown and described our system in a preferred form, changes may be made without departing from the scope of the invention, as sought to be defined in the follownig claims. In the claims, the reference to automatic compensation for change in web speed means approximate rather than exact compensation.

We claim:

1. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the Web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web While it is moving slowly, and means including an electric eye web scanner .to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, and means driven by the apparatus at a speed proportional to the web speed to vary the trigger timing lead in order to compensate for any change in average web speed.

2. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, a storage capacitor .to momentarily supply a high clamp voltage to the clamp magnet, and a source of much lower holding voltage for the clamp magnet.

3. A system for feeding a moving web through webtreating apparatus which operates on the Web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the Web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, means to cause release of the clamp, and additional safety means to release the clamp after a time interval substantially exceeding the maximum interval for normal release of the clamp.

4. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registeration with a previous operation on the Web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, and means including an electric eye Web scanner to trigger the clamp, a phase micrometer driven by the apparatus to provide a live gate within which the scanner pulse must fall in order to be effective to operate the clamp, and means responsive to the trailing edge of the live gate to release the clamp.

5. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the Web while it is moving slowly, and means including an electric eye web scanner to trigger the clamp, a phase micrometer driven by the apparatus to apparatus intermittently,

provide a live gate within which the scanner pulse must fall in order to be effective to operate the clamp, means responsive to the trailing edge of the live gate to release the clamp, said clamp being electromagnetically actuated, and an additional safety means to cut out the holding voltage after a time interval substantially exceeding the maximum interval for normal release of the clamp by means of the live gate.

6. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed, mechanism including feed rollers to move the web through the a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, means driven by the apparatus to vary the trigger timing lead in order to compensate for any change in average web speed, a storage capacitor to momentarily supply a high clamp voltage to the clamp magnet, and a source of much lower holding voltage for the clamp magnet.

7. A system for feeding a moving web through webtreating apparatus which operates on the web stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, a storage capacitor to momentarily supply a high clamp voltage to the clamp magnet, a source of much lower holding voltage for the clamp magnet, a phase micrometer driven by the apparatus to provide a live gate within which the scanner pulse must fall in order to be effective to operate the clamp, and means responsive to the trailing edge of the live gate to release the clamp.

8. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, a storage capacitor to momentarily supply a high clamp voltage to the clamp magnet, a source of much lower holding voltage for the clamp magnet, a phase micrometer driven by the apparatus to provide a live gate within which the scanner pulse must fall in order to be effective to operate the clamp, means responsive to the trailing edge of the live gate to release the clamp, and additional safety means to cut out the holding voltage after a time interval substantially exceeding the maximum interval for normal release of the clamp by means of the live gate.

9. A system for feeding a moving web through webtreating apparatus which operates on the web stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus inter mittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, means driven by the apparatus to vary the trigger timing lead in order to compensate for any change in average web speed, a storage capacitor to momentarily supply a high clamp voltage to the clamp magnet, a source of much lower holding voltage for the clamp magnet, a phase micrometer driven by the apparatus to provide a live gate within which the scanner pulse must fall in order to be effective to operate the clamp, and means responsive to the trailing edge of the live gate to release the clamp.

10. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allowtime for the clamp to operate, means driven by the apparatus to vary the trigger timing lead in order to compensate for any change in average web speed, a storage capacitor to momentarily supply a high clamp voltage to the clamp magnet, a source of much lower holding voltage for the clamp magnet, a phase micrometer driven by the apparatus to provide a live gate within which the scanner pulse must fall in order to be efiiective to operate the clamp, means responsive to the trailing edge of the live gate to release the clamp, and additional safety means to cut out the holding voltage after a time interval substantially exceeding the maximum interval for normal release of the clamp by means of the live gate.

11. A system as defined in claim 1, in which the intermittent web feed mechanism includes a cam so shaped that the cycle produced by rotation of the cam includes acceleration, deceleration, approximately uniform low velocity, stoppage, and dwell of the web, and in which the scanner triggers the clamp during the aforesaid low velocity movement of the web.

12. A system as defined in claim 2, in which the intermittent web feed mechanism includes a cam so shaped that the cycle produced by rotation of the cam includes acceleration, deceleration, approximately uniform low velocity, stoppage, and dwell of the web, and in which the scanner triggers the clamp during the aforesaid low velocity movement of the web.

13. A system as defined in claim 4, in which the intermittent web feed mechanism includes a cam so shaped that the cycle produced by rotation of the cam includes acceleration, deceleration, approximately uniform low velocity, stoppage, and dwell of the web, and in which the scanner triggers the clamp during the aforesaid low velocity movement of the web.

14. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web while it is moving slowly, and means including an electric eye web scanner having an output pulse, a Schmidt trigger circuit, a mono-stable multi-vibrator, and a cascaded power amplifier, said clamp being electromagnetically actuated, and said scanner output pulse being supplied to said Schmidt trigger circuit, the output pulse of which triggers the mono-stable multivibrator, the output of which is greatly amplified through said cascaded power amplifier in order to energize the clamp, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate.

15. A system as defined in claim 14 in which a phase micrometer produces a live gate which is supplied to a flip-flop circuit, the output of which is connected to an AND gate, means whereby the other input to the said AND gate is derived from the aforesaid mono-stable multi-vibrator only when the proper target web pulse is received, the output of said AND gate being connected to the aforesaid amplifier, and the trailing edge of the live gate serving to reset the flip-flop circuit and to thereby deenergize the clamp.

16. A system as defined in claim 15 in which the scanner is so positioned as to introduce excess lead time in the operation of the clamp, and a delay circuit which is introduced between the aforesaid Schmidt trigger and the mono-stable multi-vibrator in order to establish the correct lead time.

17. A system as defined in claim 16 in which said delay circuit has a variable delay depending on the voltage supplied to it from a voltage supply, and a potentiometer in series with said voltage supply which potentiometer may be adjusted to vary the delay in the operation of the clamp.

18. A system as defined in claim 14 in which the scanner is so positioned as to introduce excess lead time in the operation of the clamp, and a delay circuit is introduced between the aforesaid Schmidt trigger and the mono-stable multi-vibrator to establish the correct lead time, and in which said delay circuit has a variable de ay depending on the voltage supplied to it, and in which a voltage tachometer is mechanically connected to be driven at a speed proportional to the web speed and serves as a voltage supply for the aforesaid delay circuit, so that there is automatic compensation in the amount of delay in the event of a change in web speed.

19. A system as defined in claim 18 in which a phase micrometer produces a live gate which is supplied to a flipflop circuit, the output of which is connected to an AND gate, means whereby the other input to the said AND gate is derived from the aforesaid mono-stable multi-vibrator only when the proper target web pulse is received, the output of said AND gate being connected to the aforesaid amplifier, the trailing edge of the live gate serving to reset the flip-flop circuit and to thereby deenergize the clamp.

20. A system as defined in claim 19, in which the intermittent web feed mechanism includes a cam so shaped that the cycle produced by rotation of the cam includes acceleration, deceleration, approximately uniform low velocity, stoppage, and dwell of the web, and in which the scanner triggers the clamp during the aforesaid low velocity movement of the web.

21. A system for feeding a moving web through webtreating apparatus which operates on the web when stationary and for causing said operation to be in proper registration with a previous operation on the web, said apparatus comprising an intermittent web feed mechanism including feed rollers to move the web through the apparatus intermittently, a clamp preceding the apparatus to momentarily clamp the web While it is moving slowly, means including an electric eye web scanner to trigger the clamp, said clamp being electromagnetically actuated, said scanner serving to trigger said clamp slightly ahead to allow time for the clamp to operate, the intermittent web feed mechanism including a cam so shaped that the cycle produced by rotation of the cam includes acceleration,- deceleration, approximately uniform low velocity, stoppage, and dwell of the web, and said scanner serving to trigger the clamp during the aforesaid low velocity movement of the web.

References Cited by the Examiner UNITED STATES PATENTS 736,783 8/1903 Robinson et al. 22633 1,898,723 2/1933 Fuller 22633 2,737,387 3/1956 Harris et al 22633 2,746,752 5/1956 Keller et al 226-33 X ROBERT B. REEVES, Primary Examiner. HADD S. LANE, Examiner. 

1. A SYSTEM FOR FEEDING A MOVING WEB THROUGH WEBTREATING APPARATUS WHICH OPERATES ON THE WEB WHEN STATIONARY AND FOR CAUSING SAID OPERATION TO BE IN PROPER REGISTRATION WITH A PREVIOUS OPERATION ON THE WEB, SAID APPARATUS COMPRISING AN INTERMITTENT WEB FEED MECHANISM INCLUDING FEED ROLLERS TO MOVE THE WEB THROUGH THE APPARATUS INTERMITTENTLY, A CLAMP PRECEDING THE APPARATUS TO MOMENTARILY CLAMP THE WEB WHILE IT IS MOVING SLOWLY, AND MEANS INCLUDING AN ELECTRIC EYE WEB SCANNER TO TRIGGER THE CLAMP, SAID CLAMP BEING ELECTROMAGNETICALLY ACTUATED, SAID SCANNER SERVING TO TRIGGER SAID CLAMP SLIGHTLY AHEAD TO ALLOW TIME FOR THE CLAMP TO OPERATE, AND MEANS DRIVEN BY THE APPARATUS AT A SPEED PROPORTIONAL TO THE WEB SPEED TO VARY THE TRIGGER TIMING LEAD IN ORDER TO COMPENSATE FOR ANY CHARGE IN AVERAGE WEB SPEED. 